The svc_*() and
clnt_*() functions described in this page are the
old, TS-RPC interface to the XDR and RPC library, and exist
for backward compatibility. The new interface is described
in the pages referenced fromrpc(3).
These routines
allow C programs to make procedure calls on other machines
across the network. First, the client calls a procedure to
send a data packet to the server. Upon receipt of the
packet, the server calls a dispatch routine to perform the
requested service, and then sends back a reply. Finally, the
procedure call returns to the client.
Routines that
are used for Secure RPC (DES authentication) are described
in rpc_secure(3). Secure RPC can be used only if DES
encryption is available.
void
auth_destroy(AUTH *auth)
A macro that
destroys the authentication information associated with
auth. Destruction usually involves deallocation of
private data structures. The use of auth is undefined
after calling auth_destroy().
AUTH *
authnone_create()
Create and
return an RPC authentication handle that passes nonusable
authentication information with each remote procedure call.
This is the default authentication used by RPC.
AUTH *
authunix_create(char *host, int uid,
int gid, int len, int *aup_gids)
Create and
return an RPC authentication handle that contains UNIX
authentication information. The host argument is the
name of the machine on which the information was created;
uid is the user’s user ID; gid is the
user’s current group ID; len and
aup_gids refer to a counted array of groups to which
the user belongs. It is easy to impersonate a user.
AUTH *
authunix_create_default()
Calls
authunix_create() with the appropriate arguments.
Call the remote
procedure associated with prognum, versnum,
and procnum on the machine host. The in
argument is the address of the procedure’s
argument(s), and out is the address of where to place
the result(s); inproc is used to encode the
procedure’s arguments, and outproc is used to
decode the procedure’s results. This routine returns
zero if it succeeds, or the value of enum clnt_stat
cast to an integer if it fails. The routine
clnt_perrno() is handy for translating failure
statuses into messages.
Warning:
calling remote procedures with this routine uses UDP/IP as a
transport; see clntudp_create() for restrictions. You
do not have control of timeouts or authentication using this
routine.
Like
callrpc(), except the call message is broadcast to
all locally connected broadcast nets. Each time it receives
a response, this routine calls eachresult(), whose
form is:
where
out is the same as out passed to
clnt_broadcast(), except that the remote
procedure’s output is decoded there; addr
points to the address of the machine that sent the results.
If eachresult() returns zero, clnt_broadcast()
waits for more replies; otherwise it returns with
appropriate status.
Warning:
broadcast sockets are limited in size to the maximum
transfer unit of the data link. For ethernet, this value is
1500 bytes.
A macro that
calls the remote procedure procnum associated with
the client handle, clnt, which is obtained with an
RPC client creation routine such as clnt_create().
The in argument is the address of the
procedure’s argument(s), and out is the address
of where to place the result(s); inproc is used to
encode the procedure’s arguments, and outproc
is used to decode the procedure’s results; tout
is the time allowed for results to come back.
voidclnt_destroy(CLIENT *clnt)
A macro that
destroys the client’s RPC handle. Destruction usually
involves deallocation of private data structures, including
clnt itself. Use of clnt is undefined after
calling clnt_destroy(). If the RPC library opened the
associated socket, it will close it also. Otherwise, the
socket remains open.
Generic client
creation routine. The host argument identifies the
name of the remote host where the server is located. The
proto argument indicates which kind of transport
protocol to use. The currently supported values for this
field are "udp" and "tcp". Default
timeouts are set, but can be modified using
clnt_control().
Warning: Using
UDP has its shortcomings. Since UDP−based RPC messages
can only hold up to 8 Kbytes of encoded data, this transport
cannot be used for procedures that take large arguments or
return huge results.
A macro used to
change or retrieve various information about a client
object. The req argument indicates the type of
operation, and info is a pointer to the information.
For both UDP and TCP, the supported values of req and
their argument types and what they do are:
CLSET_TIMEOUT
struct timeval
set total timeout
CLGET_TIMEOUT
struct timeval
get total timeout
Note: if you
set the timeout using clnt_control(), the timeout
argument passed to clnt_call() will be ignored in all
future calls.
CLGET_SERVER_ADDR
struct sockaddr_in
get server’s address
The following
operations are valid for UDP only:
CLSET_RETRY_TIMEOUT
struct timeval
set the retry timeout
CLGET_RETRY_TIMEOUT
struct timeval
get the retry timeout
The retry
timeout is the time that UDP RPC waits for the server to
reply before retransmitting the request.
A macro that
frees any data allocated by the RPC/XDR system when it
decoded the results of an RPC call. The out argument
is the address of the results, and outproc is the XDR
routine describing the results. This routine returns one if
the results were successfully freed, and zero otherwise.
A macro that
copies the error structure out of the client handle to the
structure at address errp.
void
clnt_pcreateerror(char *s)
prints a
message to standard error indicating why a client RPC handle
could not be created. The message is prepended with string
s and a colon. A newline is appended at the end of
the message. Used when a clnt_create(),
clntraw_create(), clnttcp_create(), or
clntudp_create() call fails.
void
clnt_perrno(enum clnt_stat stat)
Print a message
to standard error corresponding to the condition indicated
by stat. A newline is appended at the end of the
message. Used after callrpc().
voidclnt_perror(CLIENT *clnt, char *s)
Print a message
to standard error indicating why an RPC call failed;
clnt is the handle used to do the call. The message
is prepended with string s and a colon. A newline is
appended at the end of the message. Used after
clnt_call().
char *
clnt_spcreateerror(char *s)
Like
clnt_pcreateerror(), except that it returns a string
instead of printing to the standard error.
Bugs: returns
pointer to static data that is overwritten on each call.
char *
clnt_sperrno(enum clnt_stat stat)
Take the same
arguments as clnt_perrno(), but instead of sending a
message to the standard error indicating why an RPC call
failed, return a pointer to a string which contains the
message.
The
clnt_sperrno() function is used instead of
clnt_perrno() if the program does not have a standard
error (as a program running as a server quite likely does
not), or if the programmer does not want the message to be
output with printf(), or if a message format
different from that supported by clnt_perrno() is to
be used.
Note: unlike
clnt_sperror() and clnt_spcreateerror(),
clnt_sperrno() returns pointer to static data, but
the result will not get overwritten on each call.
char *
clnt_sperror(CLIENT *rpch, char *s)
Like
clnt_perror(), except that (like
clnt_sperrno()) it returns a string instead of
printing to standard error.
Bugs: returns
pointer to static data that is overwritten on each call.
This routine
creates a toy RPC client for the remote program
prognum, version versnum. The transport used
to pass messages to the service is actually a buffer within
the process’s address space, so the corresponding RPC
server should live in the same address space; see
svcraw_create(). This allows simulation of RPC and
acquisition of RPC overheads, such as round trip times,
without any kernel interference. This routine returns NULL
if it fails.
This routine
creates an RPC client for the remote program prognum,
version versnum; the client uses TCP/IP as a
transport. The remote program is located at Internet address
addr. If addr−>sin_port is zero, then
it is set to the actual port that the remote program is
listening on (the remote rpcbind(8) service is consulted for
this information). The sockp argument is a socket; if
it is RPC_ANYSOCK, then this routine opens a new one and
sets sockp. Since TCP−based RPC uses buffered
I/O, the user may specify the size of the send and receive
buffers with the sendsz and recvsz arguments;
values of zero choose suitable defaults. This routine
returns NULL if it fails.
This routine
creates an RPC client for the remote program prognum,
version versnum; the client uses UDP/IP as a
transport. The remote program is located at Internet address
addr. If addr−>sin_port is zero, then
it is set to actual port that the remote program is
listening on (the remote rpcbind(8) service is consulted for
this information). The sockp argument is a socket; if
it is RPC_ANYSOCK, then this routine opens a new one and
sets sockp. The UDP transport resends the call
message in intervals of wait time until a response is
received or until the call times out. The total time for the
call to time out is specified by clnt_call().
Warning: since
UDP−based RPC messages can only hold up to 8 Kbytes of
encoded data, this transport cannot be used for procedures
that take large arguments or return huge results.
CLIENT *
clntudp_bufcreate(struct sockaddr_in *addr,
u_long prognum, u_long versnum,
struct timeval wait,
int *sockp,
unsigned int sendsize,
unsigned int recosize)
This routine
creates an RPC client for the remote program prognum,
on versnum; the client uses UDP/IP as a transport.
The remote program is located at Internet address
addr. If addr−>sin_port is zero, then
it is set to actual port that the remote program is
listening on (the remote rpcbind(8) service is consulted for
this information). The sockp argument is a socket; if
it is RPC_ANYSOCK, then this routine opens a new one and
sets sockp. The UDP transport resends the call
message in intervals of wait time until a response is
received or until the call times out. The total time for the
call to time out is specified by clnt_call().
This allows the
user to specify the maximum packet size for sending and
receiving UDP−based RPC messages.
This routine
creates an RPC client for the local program prognum,
version versnum; the client uses UNIX-domain sockets
as a transport. The local program is located at the
*raddr. The sockp argument is a socket; if it
is RPC_ANYSOCK, then this routine opens a new one and sets
sockp. Since UNIX-based RPC uses buffered I/O, the
user may specify the size of the send and receive buffers
with the sendsz and recvsz arguments; values
of zero choose suitable defaults. This routine returns NULL
if it fails.
int
get_myaddress(struct sockaddr_in *addr)
Stuff the
machine’s IP address into addr, without
consulting the library routines that deal with
/etc/hosts. The port number is always set to
htons(PMAPPORT). Returns zero on success,
non-zero on failure.
A user
interface to the rpcbind(8) service, which returns a list of
the current RPC program−to−port mappings on the
host located at IP address addr. This routine can
return NULL. The command ’’rpcinfo
−p’’ uses this routine.
A user
interface to the rpcbind(8) service, which returns the port
number on which waits a service that supports program number
prognum, version versnum, and speaks the
transport protocol associated with protocol. The
value of protocol is most likely IPPROTO_UDP or
IPPROTO_TCP. A return value of zero means that the mapping
does not exist or that the RPC system failed to contact the
remote rpcbind(8) service. In the latter case, the global
variable rpc_createerr contains the RPC status.
A user
interface to the rpcbind(8) service, which instructs
rpcbind(8) on the host at IP address addr to make an
RPC call on your behalf to a procedure on that host. The
portp argument will be modified to the
program’s port number if the procedure succeeds. The
definitions of other arguments are discussed in
callrpc() and clnt_call(). This procedure
should be used for a ’’ping’’ and
nothing else. See also clnt_broadcast().
A user
interface to the rpcbind(8) service, which establishes a
mapping between the triple (prognum, versnum,
protocol) and port on the machine’s
rpcbind(8) service. The value of protocol is most
likely IPPROTO_UDP or IPPROTO_TCP. This routine returns one
if it succeeds, zero otherwise. Automatically done by
svc_register().
bool_tpmap_unset(u_long prognum, u_long
versnum)
A user
interface to the rpcbind(8) service, which destroys all
mapping between the triple (prognum, versnum,
*) and ports on the machine’s rpcbind(8)
service. This routine returns one if it succeeds, zero
otherwise.
Register
procedure procname with the RPC service package. If a
request arrives for program prognum, version
versnum, and procedure procnum,
procname is called with a pointer to its argument(s);
progname should return a pointer to its static
result(s); inproc is used to decode the arguments
while outproc is used to encode the results. This
routine returns zero if the registration succeeded, −1
otherwise.
Warning: remote
procedures registered in this form are accessed using the
UDP/IP transport; see svcudp_create() for
restrictions.
struct rpc_createerr
rpc_createerr;
A global
variable whose value is set by any RPC client creation
routine that does not succeed. Use the routine
clnt_pcreateerror() to print the reason why.
bool_tsvc_destroy(SVCXPRT * xprt)
A macro that
destroys the RPC service transport handle, xprt.
Destruction usually involves deallocation of private data
structures, including xprt itself. Use of xprt
is undefined after calling this routine.
fd_set svc_fdset;
A global
variable reflecting the RPC service side’s read file
descriptor bit mask; it is suitable as a template argument
to the select(2) system call. This is only of interest if a
service implementor does not call svc_run(), but
rather does his own asynchronous event processing. This
variable is read−only (do not pass its address to
select(2)!), yet it may change after calls to
svc_getreqset() or any creation routines. As well,
note that if the process has descriptor limits which are
extended beyond FD_SETSIZE, this variable will only be
usable for the first FD_SETSIZE descriptors.
int svc_fds;
Similar to
svc_fdset, but limited to 32 descriptors. This
interface is obsoleted by svc_fdset.
A macro that
frees any data allocated by the RPC/XDR system when it
decoded the arguments to a service procedure using
svc_getargs(). This routine returns 1 if the results
were successfully freed, and zero otherwise.
A macro that
decodes the arguments of an RPC request associated with the
RPC service transport handle, xprt. The in
argument is the address where the arguments will be placed;
inproc is the XDR routine used to decode the
arguments. This routine returns one if decoding succeeds,
and zero otherwise.
struct sockaddr_in *
svc_getcaller(SVCXPRT *xprt)
The approved
way of getting the network address of the caller of a
procedure associated with the RPC service transport handle,
xprt.
voidsvc_getreqset(fd_set *rdfds)
This routine is
only of interest if a service implementor does not call
svc_run(), but instead implements custom asynchronous
event processing. It is called when the select(2) system
call has determined that an RPC request has arrived on some
RPC socket(s); rdfds is the resultant read file
descriptor bit mask. The routine returns when all sockets
associated with the value of rdfds have been
serviced.
voidsvc_getreq(int rdfds)
Similar to
svc_getreqset(), but limited to 32 descriptors. This
interface is obsoleted by svc_getreqset().
Associates
prognum and versnum with the service dispatch
procedure, dispatch(). If protocol is zero,
the service is not registered with the rpcbind(8) service.
If protocol is non-zero, then a mapping of the triple
(prognum, versnum, protocol) to
xprt−>xp_port is established with the local
rpcbind(8) service (generally protocol is zero,
IPPROTO_UDP or IPPROTO_TCP). The procedure dispatch()
has the following form:
The
svc_register() routine returns one if it succeeds,
and zero otherwise.
svc_run()
This routine
never returns. It waits for RPC requests to arrive, and
calls the appropriate service procedure using
svc_getreq() when one arrives. This procedure is
usually waiting for a select(2) system call to return.
Called by an
RPC service’s dispatch routine to send the results of
a remote procedure call. The xprt argument is the
request’s associated transport handle; outproc
is the XDR routine which is used to encode the results; and
out is the address of the results. This routine
returns one if it succeeds, zero otherwise.
Called when the
desired version of a program is not registered with the RPC
package. Service implementors usually do not need this
routine.
void
svcerr_systemerr(SVCXPRT *xprt)
Called by a
service dispatch routine when it detects a system error not
covered by any particular protocol. For example, if a
service can no longer allocate storage, it may call this
routine.
void
svcerr_weakauth(SVCXPRT *xprt)
Called by a
service dispatch routine that refuses to perform a remote
procedure call due to insufficient authentication arguments.
The routine calls svcerr_auth(xprt,
AUTH_TOOWEAK).
SVCXPRT *
svcraw_create(void)
This routine
creates a toy RPC service transport, to which it returns a
pointer. The transport is really a buffer within the
process’s address space, so the corresponding RPC
client should live in the same address space; see
clntraw_create(). This routine allows simulation of
RPC and acquisition of RPC overheads (such as round trip
times), without any kernel interference. This routine
returns NULL if it fails.
This routine
creates a TCP/IP−based RPC service transport, to which
it returns a pointer. The transport is associated with the
socket sock, which may be RPC_ANYSOCK, in which case
a new socket is created. If the socket is not bound to a
local TCP port, then this routine binds it to an arbitrary
port. Upon completion, xprt−>xp_fd is the
transport’s socket descriptor, and
xprt−>xp_port is the transport’s port
number. This routine returns NULL if it fails. Since
TCP−based RPC uses buffered I/O, users may specify the
size of buffers; values of zero choose suitable
defaults.
This routine
creates a UNIX-based RPC service transport, to which it
returns a pointer. The transport is associated with the
socket sock, which may be RPC_ANYSOCK, in which case
a new socket is created. The *path argument is a
variable-length file system pathname of at most 104
characters. This file is not removed when the socket
is closed. The unlink(2) system call must be used to remove
the file. Upon completion, xprt−>xp_fd is
the transport’s socket descriptor. This routine
returns NULL if it fails. Since UNIX-based RPC uses buffered
I/O, users may specify the size of buffers; values of zero
choose suitable defaults.
Create a
service on top of any open descriptor. The sendsize
and recvsize arguments indicate sizes for the send
and receive buffers. If they are zero, a reasonable default
is chosen.
Create a
service on top of any open descriptor. Typically, this
descriptor is a connected socket for a stream protocol such
as TCP. The sendsize and recvsize arguments
indicate sizes for the send and receive buffers. If they are
zero, a reasonable default is chosen.
This routine
creates a UDP/IP−based RPC service transport, to which
it returns a pointer. The transport is associated with the
socket sock, which may be RPC_ANYSOCK, in which case
a new socket is created. If the socket is not bound to a
local UDP port, then this routine binds it to an arbitrary
port. Upon completion, xprt−>xp_fd is the
transport’s socket descriptor, and
xprt−>xp_port is the transport’s port
number. This routine returns NULL if it fails.
This allows the
user to specify the maximum packet size for sending and
receiving UDP−based RPC messages.
Used for
describing UNIX credentials. This routine is useful for
users who wish to generate these credentials without using
the RPC authentication package.
Used for
describing RPC authentication information messages. This
routine is useful for users who wish to generate
RPC−style messages without using the RPC package.
Used for
describing arguments to various rpcbind(8) procedures,
externally. This routine is useful for users who wish to
generate these arguments without using the pmap_*()
interface.
Used for
describing a list of port mappings, externally. This routine
is useful for users who wish to generate these arguments
without using the pmap_*() interface.
Used for
describing RPC reply messages. This routine is useful for
users who wish to generate RPC style messages without using
the RPC package.
void
xprt_register(SVCXPRT *xprt)
After RPC
service transport handles are created, they should register
themselves with the RPC service package. This routine
modifies the global variable svc_fds. Service
implementors usually do not need this routine.
void
xprt_unregister(SVCXPRT *xprt)
Before an RPC
service transport handle is destroyed, it should unregister
itself with the RPC service package. This routine modifies
the global variable svc_fds. Service implementors
usually do not need this routine.